1. Field of the Invention
The present invention relates to an improved cutting tooth which is commonly used in sawmills to process raw logs. More particularly, the present invention relates to a high impact resistant carbide tip for an inserted tooth circular saw wherein the tip is composed of tungsten carbide, cobalt and tantalum carbide.
2. The Prior Art
The sawmill industry is the initial step in the processing of dimensional lumber. The industry generally employs steel inserted tooth circular saws to cut the bark off the raw logs. Afterwards, the resaw industry employs carbide-tipped saws to further process the lumber.
The carbide currently used in the resaw industry has a low impact resistance to the hard materials, such as sand, grit and gravel, normally encountered in the bark of raw logs and thus has a tendency to shatter upon impact with these materials. The above low impact grade of carbide is an alloy consisting of 96% tungsten carbide and 4% cobalt, and has been used extensively by the resaw industry because of the longer sharpening life provided by the high percentage of tungsten carbide in the alloy. Heretofore, the sawmill industry has considered the use of carbide for their inserted tooth saws to be unfeasible.
Although, the currently used steel inserted teeth for the saws do not generally shatter during the primary sawing operation, it is necessary to sharpen the tips after cutting 2500 board feet of lumber. These conventional tips (teeth) also have to be completely replaced approximately once a week.
A preliminary search was conducted on the present invention and the following patents were found in the search:
Re. 32,380--Wentorf, Jr., et al.,
1,904,568--Taylor,
2,053,977--Taylor,
2,121,448--Ritzau,
2,791,248--Beale,
3,171,192--Ortner et al.,
3,343,308--Fessel,
3,451,791--Meadows,
3,496,973--Ballard,
3,730,038--Farb,
3,745,623--Wentorf, Jr. et al.,
3,766,808--Cremisio et al.,
3,850,053--Bovenkerk,
3,982,911--Lee,
4,046,517--Soga,
4,225,322--Knemeyer,
4,324,163--LaVelle,
4,352,840--Sievers,
4,394,170--Sawaoka et al.,
4,439,470--Sievers,
4,399,198--Lomax et al.,
4,466,829--Nishigaki et al.,
4,637,370--Ishizuka,
4,656,099--Sievers,
4,690,024--Chaconas.
U.S. Pat. No. 4,690,024 to Chaconas, U.S. Pat. No. 4,324,163 to LaVelle, and U.S. Pat. No. 3,730,038 to Farb, claim a circular saw blade tip made of tungsten carbide.
U.S. Pat. No. 3,766,808 to Cremisio et al. discloses a bimetal saw.
U.S. Pat. No. 4,656,099 to Sievers, U.S. Pat. No. 4,046,517 to Soga, U.S. Pat. No. 3,982,911 to Lee, and U.S. Pat. No. 3,171,192 to Ortner et al., disclose abrasive carbides. The list of materials used include tungsten carbide, tantalum carbide, and cobalt.
U.S. Pat. No. Re. 32,380 to Wentorf, Jr., et al., U.S. Pat. No. 4,225,322 to Knemeyer, U.S. Pat. No. 3,850,053 to Bovenkerk, and U.S. Pat. No. 3,745,623 to Wentorf, Jr., et al, disclose diamond tools containing tungsten carbide, tantalum carbide and cobalt.
U.S. Pat. No. 4,439,470 to Sievers, U.S. Pat. No. 4,399,198 to Lomax et al., and U.S. Pat. No. 4,394,170 to Sawaoka et al, disclose a composite of metals which includes tungsten carbide, cobalt and tantalum carbide.
U.S. Pat. No. 3,496,973 to Ballard, discloses a circular saw with a lamination of tungsten carbide grit and cobalt.
U.S. Pat. No. 3,343,308 to Fessel, discloses a circular saw. The teeth of the saw are made of tungsten carbide. Note FIG. 9.
U.S. Pat. No. 4,466,829 to Nishigaki et al., U.S. Pat. No. 4,352,840 to Sievers, U.S. Pat. No. 3,451,791 to Meadows, U.S. Pat. No. 2,121,448 to Ritzau, and U.S. Pat. No. 1,904,568 to Taylor, disclose tools which contain tungsten carbide, cobalt, or tantalum carbide.
In summary, no patents were found where the replaceable teeth (or the tips thereof) were made of tungsten carbide, cobalt, and tantalum carbide. In fact, no saw blade per se was uncovered including these three ingredients.